A fuel injector is provided with plural injection ports injecting a fuel toward a combustion chamber. According to Japanese Patent No. 4069750, in the above fuel injector, an inner diameter of an injection port (intake injection port) pointing to an intake area of the combustion chamber is less than an inner diameter of an injection port (exhaust injection port) pointing to an exhaust area of the combustion chamber. Therefore, a mixed gas of the fuel and air in the combustion chamber is homogenized.
However, in the fuel injector according to Japanese Patent No. 4069750, since the inner diameter of the intake injection port is less than the inner diameter of the exhaust injection port, a penetration of a spray of the fuel injected from the intake injection port is less than a penetration of a spray of the fuel injected from the exhaust injection port. Then, in an internal combustion engine, it is difficult that the fuel enters and is completely mixed with the whole air flowing at a high flow rate in the intake area of the combustion chamber. In contrast, since the spray of the fuel injected from the exhaust injection port having the inner diameter greater than that of the intake injection port has a high penetration, the fuel may go through the air having a low flow rate in the exhaust area of the combustion chamber. As a result, it is difficult that the fuel is mixed with the air.
Further, in the fuel injector, the penetration of the spray of the fuel is adjusted by changing the inner diameter of the intake injection port or the exhaust injection port. A quantity of the fuel flowing through the intake injection port is less than a quantity of the fuel flowing through the exhaust injection port. Therefore, even though the quantity of the fuel is corrected by an arrangement or the number of the intake injection port and the exhaust injection port, it is difficult that each injection port supplies an optimal quantity of the fuel in different pointing directions.